1. Field of the Invention
This invention relates to clips used to hold tubes which are subjected to high-temperature thermal tube expansion under severe thermal transient conditions such as found in solar concentrator panels.
2. Description of the Related Art
In the past molten salt solar receivers used clips welded to the back side of the solar absorption tubes combined with a buckstay support and tie rods or rollers to support the receiver's thermal insulation dead weight while providing the normal and lateral restraint required to take out the wind and seismic loads imposed on the receiver. These solar receivers provided for free axial thermal expansion of the tubes, however they had several drawbacks, for example, the weight of the thermal insulation and buck stay was transmitted to the tubes through only two clips, imposing very severe dead weight loads on those individual clips. These solar receivers could not accommodate tube-to-tube differential expansion as might occur due to solar flux gradients across the panel during low-power conditions. The clips were not designed to accommodate the severe thermal transients imposed when clouds passed over the receiver and eventually this would lead to leakage at the clip-to-tube location due to the severe thermal stresses. Further, some of the prior designs did not afford easy removal of individual tubes.